<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			.d1 {
				width: 500px;
				height: 500px;
				border-radius: 50%;
				background-color: black;
				padding: 50px;
			}
			.d2 {
				width: 400px;
				height: 400px;
				border-radius: 50%;
				background-color: white;
				padding: 50px;
			}
			.d3 {
				width: 300px;
				height: 300px;
				border-radius: 50%;
				background-color: red;
				padding: 50px;
			}
			.d4 {
				width: 300px;
				height: 300px;
				border-radius: 50%;
				background-color: yellow;
			}
		</style>
	</head>
	<body>
		<div class="d1">
			<div class="d2">
				<div class="d3">
					<div class="d4">
						
					</div>
				</div>
			</div>
		</div>
	</body>
</html>
